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Counting Atoms

Total questions: 102

Worksheet time: 2hrs 8mins

Name
Class
Date
1.
Is this equation balanced?
a)
yes
b)
no
c)
Not enough information
2.
Is this equation balanced?
a)
yes
b)
no
c)
Not enough information
3.
What is the little number after an element in a chemical equation called.
Example: H2
a)
Coefficient 
b)
Subscript
c)
Atom
d)
Equation
4.
What is the arrow in a chemical equation...
H2 + O --> H2O
a)
Reactants
b)
Products 
c)
Yields 
d)
Chemical Equation 
5.
At the end of chemical reactions, what is the total mass of the reactants compared to the total mass of the products?
a)
the product is doubled
b)
the product is half the mass of the reactants
c)
the mass is the same
d)
the mass changes depending on the reaction
6.
What is a coefficient?
a)
The small number on the right of the chemical symbol.
b)
The large number to the left of a formula.
7.
When balancing equations a ____ can be placed to the left of a formula of a substance to make the equations balanced
a)
charge
b)
subscript
c)
random number
d)
coefficient
8.
How many atoms of aluminum are on each side of the following equation: 4Al + 3O2 --> 2Al2 O3
a)
2
b)
6
c)
1
d)
4
9.
Which side of a chemical equation is the reactant side?
a)
Left (before the yields sign)
b)
Right (after the yields sign)
10.
Which side of a chemical equation os the product side?
a)
Left (before the yields sign)
b)
Right (after the yields sign)
11.
Is the equation balanced?: 2H2O + O2 --> 4MgO + 3Fe
a)
Yes
b)
No
12.
The blue numbers in the image below represent ________
a)
Charges
b)
coefficients
c)
subscripts
d)
none of the answers are correct
13.
Number of H in 3(NH₄)₂CrO₄
a)
4
b)
6
c)
8
d)
24
14.
Which elements are(is) not balanced?
LiNO3 +CaBr2 --> Ca(NO3)2 +  LiBr   
a)
Li
b)
Ca and Li
c)
O and N
d)
Ca
15.

The elements or compounds produced by a chemical reaction

a)

reactants

b)

products

c)

inhibitor

d)

catalyst

16.

A number in front of a chemical formula that tells how many molecules or atoms involved in a reaction

a)

compound

b)

subscript

c)

coefficient

d)

replacement

17.

Matter is not created nor destroyed in any chemical or physical change

a)

closed system

b)

Law of Conservation

c)

open system

d)

chemical formula

18.

The process by which one or more substances change to produce one or more different substances

a)

chemical reaction

b)

chemical bond

c)

chemical formula

d)

chemical equation

19.

A system in which matter can enter from or escape to the surroundings

a)

open system

b)

closed system

c)

Law of conservation

d)

coefficient

20.

A system in which no matter is allowed to enter or leave

a)

decomposition

b)

open system

c)

Law of conservation of matter

d)

closed system

21.

A number in a chemical formula that tells the number of atoms in a molecule or ratio of elements in a compound

a)

subscript

b)

synthesis

c)

replacement

d)

coefficient

22.

Elements or compounds that enter into a chemical reaction

a)

inhibitor

b)

reactants

c)

catalyst

d)

products

23.

What is the part of the chemical equation in green called?

Fe + S → FeS

a)

products

b)

reactants

c)

yield

d)

input

24.

What is the right part of a chemical equation called...

2H2 + O2 --> 2H2O

a)

Reactants

b)

Products

c)

Yields

d)

Output

25.

How many different elements are in C6H12O6?

a)

1

b)

2

c)

3

d)

4

26.
An oreo cookie weighs 20 grams.  It gets crushed into crumbs for a recipe.  How much do its crumbs weigh?
a)
15 grams
b)
25 grams
c)
20 grams
27.
The total amount of matter (atoms) before and after a chemical reaction (change), remains the same.
a)
True
b)
False
28.

This is used to represent the number of each atom being represented.

a)

A Exponent

b)

The Coefficient

c)

A Molecule

d)

The Subscript

29.

A chemical reaction is balanced when

a)

both sides have the same elements

b)

both sides have the same number of atoms

c)

both sides have the same subscripts

d)

the molecules are the same on each side

30.
How much does a 5 gram Hershey's kiss weigh after it is melted in the microwave?
a)
5 grams
b)
3 grams
c)
7 grams
31.

Is the following equation balanced or unbalanced?

Fe + S2 → FeS2

a)

balanced

b)

unbalanced

32.
Is this equation balanced or unbalanced? 
H2 + O2 --> H2O
a)
balanced
b)
unbalanced
33.

In a chemical reaction,

a)

the atoms of the reactants always stay together.

b)

the atoms of the reactants rearrange, to form new products.

c)

new atoms are formed when combined to make the products

d)

some atoms disappear & others multiply to form products

34.

Students want to gather evidence for the claim that the number of atoms present before a chemical reaction is equal to the number of atoms present after the chemical reaction. They decide to react vinegar and baking soda in a sealed bag. Which of the following would provide the evidence the students need?

a)

The mass of the plastic bag, baking soda, and vinegar before the reaction was equal to the mass after the reaction.

b)

Bubbles were produced during the reaction, which meant that a gas was being produced.

c)

The plastic bag did not change in any way, indicating that it was involved in the reaction.

d)

The mass of the baking soda was exactly equal to the mass of the vinegar used to create the chemical reaction.

35.
In a reaction A + B ----> C,  reactant A has 5g and product  C has 9g. How many grams does reactant B should have? 
a)
4g
b)
5g
c)
9g
d)
14g
36.

Which Chemical Equation is Balanced?

a)

CH₄+O₂------CO₂+2H₂O

b)

H₂+O₂-----2H₂O₄

c)

4Al+3O₂-----2Al₂O₃

37.
How many nitrogen atoms does NH3 have?
a)
1
b)
2
c)
3
d)
4
38.
How many oxygen atoms are in this chemical formula?
a)
6 oxygen atoms
b)
2 oxygen atoms
c)
3 oxygen atoms
d)
4 oxygen atoms
39.
Bob puts 200 grams of ice into a pitcher with 900 grams of water. He gets distracted and comes back later to find that the ice has melted in the water. How many grams of water does Bob now have in the pitcher?
a)
200 g
b)
700 g
c)
1,100 g
40.
If four hydrogen atoms react with two hydrogen atoms, how many atoms will be in the product?
a)
6
b)
4
c)
8
d)
2
41.

When a liquid evaporates it is a ______ change.

a)

physical

b)

chemical

c)

constant

d)

drastic

42.

During a chemical reaction, matter cannot be _______ or created.

a)

bought

b)

changed

c)

destroyed

d)

made

43.

__________ are the substances present before the chemical reaction takes place.

a)

product

b)

elements

c)

compound

d)

reactants

44.

The _________ are the substances present after the chemical reaction takes place.

a)

reactants

b)

compound

c)

product

d)

elements

45.

Lead nitrate & potassium iodide form lead iodide & potassium nitrate. The reactants are

a)

lead nitrate

b)

potassium iodide

c)

lead iodide

d)

potassium nitrate

46.

The mass of the reactants must _______ the mass of the products.

a)

be less than

b)

be more than

c)

be the same as

d)

change

47.

This is an example of

a)

tic tac toe

b)

an unbalanced chemical equation

c)

a balanced chemical equation

d)

4 square

48.

Does this follow the law of conservation of mass?

a)

Yes

b)

No

c)

Not enough information here

d)

Mass can't be conserved during reactions

49.
A chemical reaction happens when:
a)
Two or more molecules interact to form different molecules.
b)
Two or molecules are repelled by a source of energy
c)
Neutrons & other subatomic particles to combine to form atoms
50.
4 grams of hydrogen and 32 grams of oxygen will combine to form:
a)
36 grams of water
b)
28 grams of hydroxide
c)
32 grams of oxygen
51.
how many grams of potassium react with 16 grams of oxygen to produce 94 grams of potassium oxide
a)
78
b)
111
c)
16
d)
94
52.
24 g of magnesium reacts with 38 g of fluorine to produce _____ g magnesium fluoride
a)
62 
b)
38
c)
24
d)
14
53.
40 g of calcium reacts with 71 g of chlorine to produce _____ g of calcium chloride.
a)
111
b)
101
c)
71
d)
91
54.
Does this chemical equation support the law of conservation of mass? H2 + O2 --> H20
a)
Yes
b)
No
55.
Matter can not be created nor destroyed: it can only be
a)
Destroyed a little bit
b)
Invisible
c)
Transformed, changed
d)
None of the above
56.
Suppose a reaction were to happen in an open container in a lab.  During the reaction, the scientist observes the chemicals bubble, and produce a gas.   During the analysis the scientist notices that the reactants weighed 20 g when he started, and the product weighed 18 g.  Explain what happened.  
a)
His chemical reaction defied the law of conservation of mass
b)
The product destroyed mass during the reaction
c)
The reactants created matter during the reaction
d)
The gas that was produced was not able to be weighed since the container was open.  
57.
What will weigh more when a chemical change is complete?  The reactants before the chemical reaction, or the product after the reaction is complete?
a)
They both will weigh the same
b)
The product always weighs more than the reactant
c)
The reactant will weigh more than the product
d)
They both will loose mass after the reaction
58.
In a reaction A + B ----> C,  reactant A has 5g and product  C has 9g. How many grams does reactant B should have? 
a)
4g
b)
5g
c)
9g
d)
14g
59.
The coefficient in  3H2O is
a)
6
b)
2
c)
3
d)
5
60.
If reaction starts with 20g of reactants it should produce 
a)
a total of 40g of products
b)
a total of 10g of products
c)
a total of 80 g of products
d)
a total of 20g of products
61.
What will weigh more when a chemical change is complete?  The reactants before the chemical reaction, or the product after the reaction is complete?
a)
They both will weigh the same
b)
The product always weighs more than the reactant
c)
The reactant will weigh more than the product
d)
They both will loose mass after the reaction
62.
This type of system allows matter to flow freely in and out...
a)
Closed System
b)
Open System
63.
A boiling pot with a lid on it to keep in the energy is what type of system?
a)
Closed System
b)
Open System
64.
Since gasses weigh nothing, when they are produced in a reaction they do not have to be accounted for.  
a)
True
b)
False
65.
Which are the reactants in the following reaction?
2Mg + O2 ---> 2MgO 
a)
Mg and O
b)
MgO
c)
Mg and MgO
d)
O and MgO
66.

Which compounds are the PRODUCTS of this reaction?

a)

CO2 + H2O

b)

C6H12O6 + O2

c)

C6H12O6 + CO2

d)

H2O + O2

67.
Maria fills a bowl with 200 g of water. She puts the bowl of water in the freezer, and the water freezes. Which will most likely be the mass of the frozen water?
a)
50 g
b)
100 g
c)
200 g
d)
400 g
68.
Is this balanced?
Al + O2 → 2Al2O3
a)
Yes
b)
No
69.
Is this balanced?
2HgO → 2Hg + O2
a)
Yes
b)
No
70.
Is this chemical equation balanced?
H2 + O2 ----> H2O
a)
Yes
b)
No
71.
How many H atoms are in the following formula?
2Na + 2H2O
a)
1
b)
2
c)
3
d)
4
72.

Is oes this follow the law of conservation of mass:

Yes or No


3HgO → 2Hg + O2

a)

Yes

b)

No

73.

Does this follow the law of conservation of mass:

Yes No


Al2 + O3→ Al2O3

a)

Yes

b)

No

74.

Does this follow the law of conservation of mass:

Yes No

a)

Yes

b)

No

75.

Does this follow the law of conservation of mass:

Yes No


O3 ---> O + O2

a)

Yes

b)

No

76.

Does this follow the law of conservation of mass:

Yes No


P4 + 3 O2 ---> 2 P2O3

a)

Yes

b)

No

77.

Does this follow the law of conservation of mass:

Yes No


2HgO → 2Hg + O2

a)

Yes

b)

No

78.

Does this follow the law of conservation of mass:

Yes No


Al + O2 → 2Al2O3

a)

Yes

b)

No

79.

Does this follow the law of conservation of mass:

Yes No


H2 + 2 O2 -> 2 H2O

a)

Yes

b)

No

80.

Does this follow the law of conservation of mass:

Yes No


Na + F --> NaF

a)

Yes

b)

No

81.
How many elements does PbNO3 have?
a)
2
b)
3
c)
4
d)
5
82.
A chemical equation tells us 
a)
the reactants and the products.
b)
the elements that make up the reactants and the products.
c)
the number of atoms that make up the reactants and the products.
d)
All of the above.
83.
What is the reactant in the following equation?
2NaHCO3  -> Na2CO3  +  CO2  + H2O
a)
NaHCO3
b)
Na2CO3
c)
CO2
d)
H2O
84.
What will happen to the mass of the product if I double the mass of the reactants?
a)
It will decrease by half.
b)
It will increase by half.
c)
It will double in amount.
d)
The mass remains the same.
85.
What is the arrow in a chemical equation...
H2 + O --> H2O
a)
Reactants
b)
Products 
c)
Yields 
d)
Chemical Equation 
86.
How many O's are in Al₂(SO₄)₃
a)
4
b)
12
c)
7
d)
24
87.
12g of Carbon react with 16g of Oxygen, how much carbon monoxide (CO) is formed? 
a)
28 g
b)
4g
c)
30g
d)
12g
88.
Molecule
a)
A group of atoms bonded together
b)
Basic unit of a chemical element
c)
Coefficient
d)
Subscript
89.
3Na4
What is the subscript?
a)
1
b)
2
c)
3
d)
4
90.
3Na4
What is the coefficient?
a)
1
b)
2
c)
3
d)
4
91.

To balance a chemical equation, there must be the same number of atoms of each kind of element on both sides of the arrow.

a)

True

b)

False

92.

Which of the following is true of the compound

5 H2O

a)

5 is a coefficient

b)

2 is a coefficient

c)

5 is a subscript

d)

None are true

93.

Which of the following is true of the compound

5 H2O

a)

5 is a subscript

b)

2 is a coefficient

c)

2 is a subscript

d)

None are true

94.

How many molecules of CO2 are in the REACTANTS of this equation?

a)

4

b)

2

c)

1

d)

8

95.

In this chemical equation , CH4 and 2O2 are called the...

a)

Products

b)

Reactants

c)

Coefficient

d)

Subscript

96.

In this chemical equation , CO2 and 2H2O are called the...

a)

Products

b)

Reactants

c)

Coefficient

d)

Subscript

97.

In this chemical equation , the 2 in front of the 2O2 and the 2 in front of the 2H2O are called the...

a)

Products

b)

Reactants

c)

Coefficient

d)

Subscript

98.

In this chemical equation ,the small numbers dropped down below the letters like the 4 in CH4 are known as the

a)

Products

b)

Reactants

c)

Coefficient

d)

Subscript

99.

How many Carbons are on EACH side of the chemical reaction?

a)

1

b)

3

c)

4

d)

5

100.

There are 4 hydrogens in the products of the equation. How many hydrogens would you expect in the reactants?

a)

1

b)

3

c)

4

d)

5

101.

Looking at the reactants, there is _____ molecule(s) of CH4 and _______ molecule(s) of O2.

a)

1, 1

b)

1, 2

c)

2, 2

d)

2, 4

102.

Looking at the products , there is _____ atom(s) of Oxygen in CO2 and _______ atom(s) of Oxygen in 2H2O.

a)

1, 1

b)

1, 2

c)

2, 2

d)

2, 4

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